We propose to study the roles of the individual subunits of DNA- dependent RNA polymerase in causing the changes in gene expression responsible for intracellular differentiation in Bacillus subtilis. To study spore formation and a second developmental phenomenon, spore germination, an interwoven genetic and biochemical approach is proposed. At the biochemical level, evidence will be sought for changes in the template specificity of RNA polymerase during the course of germination by methods already successfully applied to sporulation. Using standard genetic techniques, mutants in RNA polymerase identified by defects in RNA synthesis or by resistance to RNA polymerase-specific antibiotics such as rifampicin will be analyzed for altered patterns of sporulation and germination and will be mapped with respect to known markers and with respect to each other. Purified RNA polymerase from mutant and wild-type strains will be dissociated, individual subunits will be isolated, and active enzyme will be reconstituted from selected combinations of subunits to identify the subunit altered in a given mutant. Especially interesting will be studies on mutations in the sigma factor of vegetative cells and in hypothetical sigma factors specific for sporulation and germination.